Apparatus for surfacing plate glass



July 30, 1940. R. D. BOLE ET Al.

APPARATUS FOR SRFACING PLATE GLASS Filed March 29, 1938 5 Sheets-Sheet l um H/ Lu INVE/vmgs OL E N0 M Il 1 July 30, 1940. RQ D. BOLE n AL 2,209,505

APPARATUS FORl SURFACING PLATE GLASS Filed March 29, 1958 5 Sheets-Sheet 2 @4,9 NURNEYS. i

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July 30, 1940.

R. DJBOLE El' AL APPARATUS FOR SURFACING PLATE GLASS Filed March 29, 1938 3 Sheets-Sheet 3 BY @WMS l the glass.

Patented July 30, 1940 l f ArAn'rs roasURFAoiNG .PLATE dnas si Y faalhlh). noregrittsturghlaa EiniI'A'.' finisca. i "Perrysville, Pa;g"as`signo`rs""to Bittsburgh'fPlate GlassCompany, corporation of'Iennfsylvania y lApplication Marchj29, 195.8S'erial i l j roma; (enfer-+240).j'f y y body ofthe .table .has an integral top lIrlllsuitably stiffe'ned--by ribs and above this `top and in 'par- ',allel therewith-.is a false top I51whichscarriesza glass sheet. l whichis to besuriaced; The space I'Lbetween the'plates Ill andeI5 isfolosedsatthe edges y' by lmeans of lthe flangey members -I 3V which ,lie `on all foursidesbtthe. table. yDistributed `The invention relates Yto an. apparatus for sur- `facing iplatej glassA and -particularly to glass iinishing apparatus inwhichfthefltops of: the `.cars or tables which pass `lceneathfthe* grinding .and polishing runners in the straightawaysuracing operation are. .maintained in a true horizontal plane.- During. thepolishing operation, considerable heat is developed, due to the relatively high frictional contact between the polishing pads and This heat is transmitted to the metal plates constituting the tops of the tables and causes them to bulge up slightly at the center, so that the surfaces which carry the glass are no longer in a true horizontal plane. This condition corrects itself in part during the return of the tables to the grinding end of the line after the polishing operation, but some convexity still remains, and when the table is again passed beneath the grinding runners (carrying thereon a new plate of glass or one which has been surfaced only on one side) the glass plate is reduced to uneven thickness, being ground thinner along the middle portion than along the edges at the sides of the table.

The object of the present invention is to overcome the difficulty above set forth by cooling the table tops during the period of their passage beneath the series of polishing runners, so that the increase in temperature in the tops is reduced to a minimum during this period and any tendency to warp correspondingly is reduced. This object is accomplished by the use of a false top on each table and the application of a cooling fluid to the space between such false top and the main table top therebeneath during the polishing operation. This not only keeps the false top at a lower temperature than would otherwise be the' case, but prevents the main top, which supports the false top and to which such false top is rigidly clamped throughout its area, from being ap-preciably heated and warped. Certain embodiments of the invention are illustrated in the accompanying drawings, wherein:

Figure 1 is a plan view of one form of table. Fig. 2 is a side elevation. Fig. 3 is a section on the line 11T-III of Fig. 1. Figs. 4 and 5 are enlarged sections on the line IV-IV of Fig. 1 showing two forms of spacing and clamping means. Figs. 6 and 7 illustrate a modication, Fig. 6 being a transverse section through the table and Fig. 7 an enlarged section.

Referring to Figs. 1 to 5, the numeral II indicates the body of the table which is mounted on the wheels I2 carried by the rails I3 which extend beneath the grinding and polishingrunners. The

over the area of the table are a plurality of spacers in the form of the blocks I9 which are preferably welded at their upper ends to the lower surface of the plate I5. Also distributed over the lower side of the plate I5 are the nuts welded to the plate and engaged by the anchoring bolts EI by means of which the plate I5 is pulled down tightly against the spacers' I9,

thus providing a rm support for the top plate,

gaskets being provided as indicated at 2id to in escape of lair from the space while it is beingv filled with water and so insure that the water will contact withithe lower surface of the plate'- AI5, one or more vents 26 are employed, such vents being closed by screw plugs 2l' after the filling operation is complete. In the use of the appara.-

tus, the space I'I is filled with water just before the tab-le passes beneath the polishing runners, and after the table passes this portion of the surfacing apparatus, the water is drained from the space II through the pipe 24. The use of the water in the space Il prevents the top plate l5 from becoming heated to any extent during the polishing operation so that any warping thereof is reduced to a minimum. The body of water also prevents any.r substantial amount of heat being transmitted to the plate I4 so that this' plate remains substantially flat and true at all times. Since the top plate I5 is clamped to the bottom plate throughout its area and is held positively spaced therefrom, any tendency of the top plate to become deformed due to temperature conditions is correspondingly reduced.

Figs. 6 and 7 illustrate a modification, in which provision is made for circulating a cooling fluidV ing beneath the polishing runners, thus insuring a lower temperature in the plate I5 than is the case with the construction of Figs. 1 to 5, in which there is no circulation. This constant circulation is provided by means of a pump 28 which is carried on the bottom of the table and driven from the electric motor 29. This pump has an intake 3G projecting into a trough 3|, which eX- tends the length of the polishing system. The water taken up by the pump is discharged through the pipe 32 to the space i7 and is continuously exhausted from such space through a pipe 33 which discharges into a trough 34 which also extends the length of the polishing system. In this manner a continuous flow of water through the space il is provided during the period in which the glass is being polished. In

order to provide for the automatic stopping and starting of the motor 2S, the power is supplied from a pair of rails 35 supplied with current from the leads 36. These rails begin at the point of travel of the table at which it is desired that the motor should start and terminate at the point where the table passes the last polishing runner, so that the automatic stopping and starting of the pumping action is provided for, contact brushes carried on the base of the motor engaging the rails, as shown. In order to insure that the space l1 shall be completely filled with water and, therefore, contact with the lower surface of the plate l5 throughout its area, the outlet pipe 33 leads up to a point above the lower level of the plate i5, as indicated in Fig, 7, a suitable recess 31 being provided for this purpose.

What we claim is:

A plate glass grinding and polishing table mounted for movement along a track and comprising a metal body portion having a flat rectangular upper face, a false top for the table comprising a metal plate spaced above said face in parallel therewith, positive spacing and clamping means distributed over the area of said face for maintaining the false top in xed relation to said face throughout its area, fluid supply means extending along the line of travel of the table, a motor driven pump carried by the table,

v,operation of the pump.

RALPH D. BOLE. EMIL A. FUSCA. 

